1. Field of the Invention
The present invention relates to a golf club measuring system and a golf club measuring method, each of which is able to measure physical values such as strain and torsion occurring in golf club shafts.
The present application claims priority on Japanese Patent Application No. 2011-168310, the content of which is incorporated herein by reference.
2. Description of the Related Art
Conventionally, manufacturers and dealers of golf produces have been assessing golf clubs by use of sensors attached to golf club shafts, thus measuring physical values such as strain and torsion occurring on golf club shafts. Physical values can be measured using measuring instruments by imparting a certain load to golf clubs which are fixed in position. However, it is preferable that physical values be measured with golf clubs actually being swung in order to obtain good assessment on impacts on players' swinging motions of golf club shafts or properties of golf balls being struck with golf club heads.
Various methods for assessment, analysis, and optimum selection of golf clubs have been disclosed in patent literatures (PLT) 1 to 11. PLT 1 disclosed an assessment method of dynamic behavior of a golf club shaft, wherein strain gauges are attached to two points arbitrarily selected on a golf club shaft so as to measure strain occurring between two points of a golf club shaft during the swinging motion of a golf club shaft. PLT 2 disclosed a shaft selection method for a golf club optimum to each golfer, wherein it teaches a method for selecting a golf club shaft demonstrating the ideal deflection/bending behavior and the rigidity distribution optimum to each golfer. PLT 3 disclosed a selection system of an optimum golf club shaft, wherein it teaches a method for selecting a golf club shaft demonstrating the optimum head-moving speed based on the analysis result regarding the deformation behavior of each golf club shaft. PLT 4 disclosed a golf club selection method that selects a golf club based on the measurement result of gyro-sensor units measuring the movement of hands or other body parts of each golfer swinging his/her golf club. PLT 5 disclosed a golf club shaft selection method that selects a golf club shaft whose property matches each golfer's physical feature and profile considering the head-moving speed, the swing tempo, and the ideal trajectory of a golf ball. PLT 6 disclosed a golf club information providing system that manages the relationship between the registered clients and the specifications of golf clubs matching with the clients' swinging motions, thus improving the efficiency in selecting golf clubs for clients. PLT 7 disclosed a golf club shaft selection method that selects a golf club shaft based on the measurement result of the head-moving speed and the swing tempo for each golfer with reference to the predetermined chart describing weights and behaviors of golf club shafts. PLT 8 disclosed a golfer classification method that classifies golfers based on the measurement result of physical values representing golfers' features determined by golf swing computation simulating golf club models based on three-dimensional time-series data relating to motions of golfers' hands holding grips of golf clubs, thus selecting optimum golf clubs for golfers. PLT 9 disclosed a golfer classification method, which teaches a modified technology of PLT 8 with additionally implementing head-moving speed computation. PLT 10 disclosed a golf club selection method that selects an optimum combination of a head and a shaft constituting a golf club based on the measurement result of the behavior of each golf club, which can be physically separated into a head and a shaft, before and after the striking of a golf ball with a golf club. PLT 11 disclosed a golf club shaft selection system that offers a recommended golf club shaft considering its bending point which is presumed based on the measured values of strain gauges attached to each golf club shaft.
Generally speaking, a few grams of weight attached to a head may cause a significant impact on the behavior of a golf club shaft being swung. In the foregoing measuring method, strain gauges attached to a golf club shaft are electrically connected to a strain measuring device via a wiring cable, whereby a golf club shaft may undergo variable behavior due to the weight of a wiring cable. Additionally, a golf club shaft may undergo variable behavior due to physical force applied to a wiring cable which moves in the air against the air resistance together with a golf club being swung. Therefore, the foregoing measurement method using a wiring cable may measure uncertain physical values on a golf club shaft undergoing variable behavior.